diff --git a/packages/backend-rs/src/config/server.rs b/packages/backend-rs/src/config/server.rs
index 81f2baedb0..19f4d19da0 100644
--- a/packages/backend-rs/src/config/server.rs
+++ b/packages/backend-rs/src/config/server.rs
@@ -346,7 +346,7 @@ pub fn load_config() -> Config {
         hostname,
         redis_key_prefix,
         scheme,
-        ws_scheme: ws_scheme.to_string(),
+        ws_scheme: ws_scheme.to_owned(),
     }
 }
 
diff --git a/packages/backend-rs/src/database/cache.rs b/packages/backend-rs/src/database/cache.rs
index 60abea56e8..515053ef6c 100644
--- a/packages/backend-rs/src/database/cache.rs
+++ b/packages/backend-rs/src/database/cache.rs
@@ -62,7 +62,7 @@ fn wildcard(category: Category) -> String {
 /// # use backend_rs::database::cache;
 /// # async fn f() -> Result<(), Box<dyn std::error::Error>> {
 /// let key = "apple";
-/// let data = "I want to cache this string".to_string();
+/// let data = "I want to cache this string".to_owned();
 ///
 /// // caches the data for 10 seconds
 /// cache::set(key, &data, 10).await?;
@@ -106,7 +106,7 @@ pub async fn set<V: for<'a> Deserialize<'a> + Serialize>(
 /// # use backend_rs::database::cache;
 /// # async fn f() -> Result<(), Box<dyn std::error::Error>> {
 /// let key = "banana";
-/// let data = "I want to cache this string".to_string();
+/// let data = "I want to cache this string".to_owned();
 ///
 /// // set cache
 /// cache::set(key, &data, 10).await?;
@@ -145,7 +145,7 @@ pub async fn get<V: for<'a> Deserialize<'a> + Serialize>(key: &str) -> Result<Op
 /// # use backend_rs::database::cache;
 /// # async fn f() -> Result<(), Box<dyn std::error::Error>> {
 /// let key = "chocolate";
-/// let value = "I want to cache this string".to_string();
+/// let value = "I want to cache this string".to_owned();
 ///
 /// // set cache
 /// cache::set(key, &value, 10).await?;
@@ -248,12 +248,12 @@ mod unit_test {
         let value_1: Vec<i32> = vec![1, 2, 3, 4, 5];
 
         let key_2 = "CARGO_TEST_CACHE_KEY_2";
-        let value_2 = "Hello fedizens".to_string();
+        let value_2 = "Hello fedizens".to_owned();
 
         let key_3 = "CARGO_TEST_CACHE_KEY_3";
         let value_3 = Data {
             id: 1000000007,
-            kind: "prime number".to_string(),
+            kind: "prime number".to_owned(),
         };
 
         set(key_1, &value_1, 1).await.unwrap();
@@ -287,7 +287,7 @@ mod unit_test {
         let key_2 = "fish";
         let key_3 = "awawa";
 
-        let value_1 = "hello".to_string();
+        let value_1 = "hello".to_owned();
         let value_2 = 998244353u32;
         let value_3 = 'あ';
 
diff --git a/packages/backend-rs/src/database/redis.rs b/packages/backend-rs/src/database/redis.rs
index a0fc16eea6..7fa7255b47 100644
--- a/packages/backend-rs/src/database/redis.rs
+++ b/packages/backend-rs/src/database/redis.rs
@@ -57,12 +57,12 @@ async fn init_conn_pool() -> Result<(), RedisError> {
         };
 
         if let Some(user) = &redis.user {
-            params.push(user.to_string())
+            params.push(user.to_owned())
         }
         if let Some(pass) = &redis.pass {
             params.push(format!(":{}@", urlencoding::encode(pass)))
         }
-        params.push(redis.host.to_string());
+        params.push(redis.host.to_owned());
         params.push(format!(":{}", redis.port));
         params.push(format!("/{}", redis.db));
 
@@ -111,8 +111,8 @@ pub async fn get_conn() -> Result<PooledConnection<'static, RedisConnectionManag
 
 /// prefix Redis key
 #[inline]
-pub fn key(key: impl ToString) -> String {
-    format!("{}:{}", CONFIG.redis_key_prefix, key.to_string())
+pub fn key(key: impl std::fmt::Display) -> String {
+    format!("{}:{}", CONFIG.redis_key_prefix, key)
 }
 
 #[cfg(test)]
diff --git a/packages/backend-rs/src/federation/acct.rs b/packages/backend-rs/src/federation/acct.rs
index 60c9e6f25c..1c28685cd8 100644
--- a/packages/backend-rs/src/federation/acct.rs
+++ b/packages/backend-rs/src/federation/acct.rs
@@ -25,11 +25,11 @@ impl FromStr for Acct {
         .collect();
 
         Ok(Self {
-            username: split[0].to_string(),
+            username: split[0].to_owned(),
             host: if split.len() == 1 {
                 None
             } else {
-                Some(split[1].to_string())
+                Some(split[1].to_owned())
             },
         })
     }
@@ -70,11 +70,11 @@ mod unit_test {
     #[test]
     fn acct_to_string() {
         let remote_acct = Acct {
-            username: "firefish".to_string(),
-            host: Some("example.com".to_string()),
+            username: "firefish".to_owned(),
+            host: Some("example.com".to_owned()),
         };
         let local_acct = Acct {
-            username: "MisakaMikoto".to_string(),
+            username: "MisakaMikoto".to_owned(),
             host: None,
         };
 
@@ -87,11 +87,11 @@ mod unit_test {
     #[test]
     fn string_to_acct() {
         let remote_acct = Acct {
-            username: "firefish".to_string(),
-            host: Some("example.com".to_string()),
+            username: "firefish".to_owned(),
+            host: Some("example.com".to_owned()),
         };
         let local_acct = Acct {
-            username: "MisakaMikoto".to_string(),
+            username: "MisakaMikoto".to_owned(),
             host: None,
         };
 
diff --git a/packages/backend-rs/src/federation/nodeinfo/fetch.rs b/packages/backend-rs/src/federation/nodeinfo/fetch.rs
index 4f11821054..c237a893fb 100644
--- a/packages/backend-rs/src/federation/nodeinfo/fetch.rs
+++ b/packages/backend-rs/src/federation/nodeinfo/fetch.rs
@@ -109,12 +109,12 @@ mod unit_test {
         let links_1 = NodeinfoLinks {
             links: vec![
                 NodeinfoLink {
-                    rel: "https://example.com/incorrect/schema/2.0".to_string(),
-                    href: "https://example.com/dummy".to_string(),
+                    rel: "https://example.com/incorrect/schema/2.0".to_owned(),
+                    href: "https://example.com/dummy".to_owned(),
                 },
                 NodeinfoLink {
-                    rel: "http://nodeinfo.diaspora.software/ns/schema/2.0".to_string(),
-                    href: "https://example.com/real".to_string(),
+                    rel: "http://nodeinfo.diaspora.software/ns/schema/2.0".to_owned(),
+                    href: "https://example.com/real".to_owned(),
                 },
             ],
         };
@@ -126,12 +126,12 @@ mod unit_test {
         let links_2 = NodeinfoLinks {
             links: vec![
                 NodeinfoLink {
-                    rel: "https://example.com/incorrect/schema/2.0".to_string(),
-                    href: "https://example.com/dummy".to_string(),
+                    rel: "https://example.com/incorrect/schema/2.0".to_owned(),
+                    href: "https://example.com/dummy".to_owned(),
                 },
                 NodeinfoLink {
-                    rel: "http://nodeinfo.diaspora.software/ns/schema/2.1".to_string(),
-                    href: "https://example.com/real".to_string(),
+                    rel: "http://nodeinfo.diaspora.software/ns/schema/2.1".to_owned(),
+                    href: "https://example.com/real".to_owned(),
                 },
             ],
         };
@@ -143,12 +143,12 @@ mod unit_test {
         let links_3 = NodeinfoLinks {
             links: vec![
                 NodeinfoLink {
-                    rel: "https://example.com/incorrect/schema/2.0".to_string(),
-                    href: "https://example.com/dummy/2.0".to_string(),
+                    rel: "https://example.com/incorrect/schema/2.0".to_owned(),
+                    href: "https://example.com/dummy/2.0".to_owned(),
                 },
                 NodeinfoLink {
-                    rel: "https://example.com/incorrect/schema/2.1".to_string(),
-                    href: "https://example.com/dummy/2.1".to_string(),
+                    rel: "https://example.com/incorrect/schema/2.1".to_owned(),
+                    href: "https://example.com/dummy/2.1".to_owned(),
                 },
             ],
         };
diff --git a/packages/backend-rs/src/federation/nodeinfo/generate.rs b/packages/backend-rs/src/federation/nodeinfo/generate.rs
index 80fe4bc609..c74fd55e10 100644
--- a/packages/backend-rs/src/federation/nodeinfo/generate.rs
+++ b/packages/backend-rs/src/federation/nodeinfo/generate.rs
@@ -68,45 +68,45 @@ async fn generate_nodeinfo_2_1() -> Result<Nodeinfo21, DbErr> {
     let meta = local_server_info().await?;
     let mut metadata = HashMap::from([
         (
-            "nodeName".to_string(),
+            "nodeName".to_owned(),
             json!(meta.name.unwrap_or_else(|| CONFIG.host.clone())),
         ),
-        ("nodeDescription".to_string(), json!(meta.description)),
-        ("repositoryUrl".to_string(), json!(meta.repository_url)),
+        ("nodeDescription".to_owned(), json!(meta.description)),
+        ("repositoryUrl".to_owned(), json!(meta.repository_url)),
         (
-            "enableLocalTimeline".to_string(),
+            "enableLocalTimeline".to_owned(),
             json!(!meta.disable_local_timeline),
         ),
         (
-            "enableRecommendedTimeline".to_string(),
+            "enableRecommendedTimeline".to_owned(),
             json!(!meta.disable_recommended_timeline),
         ),
         (
-            "enableGlobalTimeline".to_string(),
+            "enableGlobalTimeline".to_owned(),
             json!(!meta.disable_global_timeline),
         ),
         (
-            "enableGuestTimeline".to_string(),
+            "enableGuestTimeline".to_owned(),
             json!(meta.enable_guest_timeline),
         ),
         (
-            "maintainer".to_string(),
+            "maintainer".to_owned(),
             json!({"name":meta.maintainer_name,"email":meta.maintainer_email}),
         ),
-        ("proxyAccountName".to_string(), json!(meta.proxy_account_id)),
+        ("proxyAccountName".to_owned(), json!(meta.proxy_account_id)),
         (
-            "themeColor".to_string(),
-            json!(meta.theme_color.unwrap_or_else(|| "#31748f".to_string())),
+            "themeColor".to_owned(),
+            json!(meta.theme_color.unwrap_or_else(|| "#31748f".to_owned())),
         ),
     ]);
     metadata.shrink_to_fit();
 
     Ok(Nodeinfo21 {
         software: Software21 {
-            name: "firefish".to_string(),
+            name: "firefish".to_owned(),
             version: CONFIG.version.clone(),
             repository: Some(meta.repository_url),
-            homepage: Some("https://firefish.dev/firefish/firefish".to_string()),
+            homepage: Some("https://firefish.dev/firefish/firefish".to_owned()),
         },
         protocols: vec![Protocol::Activitypub],
         services: Services {
diff --git a/packages/backend-rs/src/init/log.rs b/packages/backend-rs/src/init/log.rs
index 47466735e3..a1dab991a4 100644
--- a/packages/backend-rs/src/init/log.rs
+++ b/packages/backend-rs/src/init/log.rs
@@ -18,15 +18,15 @@ pub fn initialize_logger() {
         });
     } else if let Some(levels) = &CONFIG.log_level {
         // `logLevel` config is Deprecated
-        if levels.contains(&"trace".to_string()) {
+        if levels.contains(&"trace".to_owned()) {
             builder = builder.with_max_level(Level::TRACE);
-        } else if levels.contains(&"debug".to_string()) {
+        } else if levels.contains(&"debug".to_owned()) {
             builder = builder.with_max_level(Level::DEBUG);
-        } else if levels.contains(&"info".to_string()) {
+        } else if levels.contains(&"info".to_owned()) {
             builder = builder.with_max_level(Level::INFO);
-        } else if levels.contains(&"warning".to_string()) {
+        } else if levels.contains(&"warning".to_owned()) {
             builder = builder.with_max_level(Level::WARN);
-        } else if levels.contains(&"error".to_string()) {
+        } else if levels.contains(&"error".to_owned()) {
             builder = builder.with_max_level(Level::ERROR);
         } else {
             // Fallback
diff --git a/packages/backend-rs/src/init/system_info.rs b/packages/backend-rs/src/init/system_info.rs
index 7fde335e85..82505a1625 100644
--- a/packages/backend-rs/src/init/system_info.rs
+++ b/packages/backend-rs/src/init/system_info.rs
@@ -26,19 +26,19 @@ pub fn show_server_info() -> Result<(), SysinfoPoisonError> {
 
     tracing::info!(
         "Hostname: {}",
-        System::host_name().unwrap_or_else(|| "unknown".to_string())
+        System::host_name().unwrap_or_else(|| "unknown".to_owned())
     );
     tracing::info!(
         "OS: {}",
-        System::long_os_version().unwrap_or_else(|| "unknown".to_string())
+        System::long_os_version().unwrap_or_else(|| "unknown".to_owned())
     );
     tracing::info!(
         "Kernel: {}",
-        System::kernel_version().unwrap_or_else(|| "unknown".to_string())
+        System::kernel_version().unwrap_or_else(|| "unknown".to_owned())
     );
     tracing::info!(
         "CPU architecture: {}",
-        System::cpu_arch().unwrap_or_else(|| "unknown".to_string())
+        System::cpu_arch().unwrap_or_else(|| "unknown".to_owned())
     );
     tracing::info!("CPU threads: {}", system_info.cpus().len());
     tracing::info!("Total memory: {} MiB", system_info.total_memory() / 1048576);
diff --git a/packages/backend-rs/src/misc/check_server_block.rs b/packages/backend-rs/src/misc/check_server_block.rs
index a6355f5e94..ecc50132ad 100644
--- a/packages/backend-rs/src/misc/check_server_block.rs
+++ b/packages/backend-rs/src/misc/check_server_block.rs
@@ -81,7 +81,7 @@ pub async fn is_allowed_server(host: &str) -> Result<bool, sea_orm::DbErr> {
         return Ok(true);
     }
     if let Some(allowed_hosts) = meta.allowed_hosts {
-        return Ok(allowed_hosts.contains(&host.to_string()));
+        return Ok(allowed_hosts.contains(&host.to_owned()));
     }
     Ok(false)
 }
diff --git a/packages/backend-rs/src/misc/check_word_mute.rs b/packages/backend-rs/src/misc/check_word_mute.rs
index fdf4e1a8a0..f4f2e1234a 100644
--- a/packages/backend-rs/src/misc/check_word_mute.rs
+++ b/packages/backend-rs/src/misc/check_word_mute.rs
@@ -73,114 +73,114 @@ mod unit_test {
     #[test]
     fn word_mute_match() {
         let texts = [
-            "The quick brown fox jumps over the lazy dog.".to_string(),
-            "色は匂へど 散りぬるを 我が世誰ぞ 常ならむ".to_string(),
-            "😇".to_string(),
+            "The quick brown fox jumps over the lazy dog.".to_owned(),
+            "色は匂へど 散りぬるを 我が世誰ぞ 常ならむ".to_owned(),
+            "😇".to_owned(),
         ];
 
-        let hiragana_1 = r"/[\u{3040}-\u{309f}]/u".to_string();
-        let hiragana_2 = r"/[あ-ん]/u".to_string();
-        let katakana_1 = r"/[\u{30a1}-\u{30ff}]/u".to_string();
-        let katakana_2 = r"/[ア-ン]/u".to_string();
-        let emoji = r"/[\u{1f300}-\u{1f5ff}\u{1f900}-\u{1f9ff}\u{1f600}-\u{1f64f}\u{1f680}-\u{1f6ff}\u{2600}-\u{26ff}\u{2700}-\u{27bf}\u{1f1e6}-\u{1f1ff}\u{1f191}-\u{1f251}\u{1f004}\u{1f0cf}\u{1f170}-\u{1f171}\u{1f17e}-\u{1f17f}\u{1f18e}\u{3030}\u{2b50}\u{2b55}\u{2934}-\u{2935}\u{2b05}-\u{2b07}\u{2b1b}-\u{2b1c}\u{3297}\u{3299}\u{303d}\u{00a9}\u{00ae}\u{2122}\u{23f3}\u{24c2}\u{23e9}-\u{23ef}\u{25b6}\u{23f8}-\u{23fa}]/u".to_string();
+        let hiragana_1 = r"/[\u{3040}-\u{309f}]/u".to_owned();
+        let hiragana_2 = r"/[あ-ん]/u".to_owned();
+        let katakana_1 = r"/[\u{30a1}-\u{30ff}]/u".to_owned();
+        let katakana_2 = r"/[ア-ン]/u".to_owned();
+        let emoji = r"/[\u{1f300}-\u{1f5ff}\u{1f900}-\u{1f9ff}\u{1f600}-\u{1f64f}\u{1f680}-\u{1f6ff}\u{2600}-\u{26ff}\u{2700}-\u{27bf}\u{1f1e6}-\u{1f1ff}\u{1f191}-\u{1f251}\u{1f004}\u{1f0cf}\u{1f170}-\u{1f171}\u{1f17e}-\u{1f17f}\u{1f18e}\u{3030}\u{2b50}\u{2b55}\u{2934}-\u{2935}\u{2b05}-\u{2b07}\u{2b1b}-\u{2b1c}\u{3297}\u{3299}\u{303d}\u{00a9}\u{00ae}\u{2122}\u{23f3}\u{24c2}\u{23e9}-\u{23ef}\u{25b6}\u{23f8}-\u{23fa}]/u".to_owned();
 
-        assert!(check_word_mute_impl(&texts, &[], &["/the/i".to_string()]));
+        assert!(check_word_mute_impl(&texts, &[], &["/the/i".to_owned()]));
 
-        assert!(!check_word_mute_impl(&texts, &[], &["/the/".to_string()]));
+        assert!(!check_word_mute_impl(&texts, &[], &["/the/".to_owned()]));
 
-        assert!(check_word_mute_impl(&texts, &[], &["/QuICk/i".to_string()]));
+        assert!(check_word_mute_impl(&texts, &[], &["/QuICk/i".to_owned()]));
 
-        assert!(!check_word_mute_impl(&texts, &[], &["/QuICk/".to_string()]));
+        assert!(!check_word_mute_impl(&texts, &[], &["/QuICk/".to_owned()]));
 
         assert!(check_word_mute_impl(
             &texts,
             &[
-                "我".to_string(),
-                "有為の奥山 今日越えて 浅き夢見し 酔ひもせず".to_string()
+                "我".to_owned(),
+                "有為の奥山 今日越えて 浅き夢見し 酔ひもせず".to_owned()
             ],
             &[]
         ));
 
         assert!(!check_word_mute_impl(
             &texts,
-            &["有為の奥山 今日越えて 浅き夢見し 酔ひもせず".to_string()],
+            &["有為の奥山 今日越えて 浅き夢見し 酔ひもせず".to_owned()],
             &[]
         ));
 
         assert!(!check_word_mute_impl(
             &texts,
             &[
-                "有為の奥山".to_string(),
-                "今日越えて".to_string(),
-                "浅き夢見し".to_string(),
-                "酔ひもせず".to_string()
+                "有為の奥山".to_owned(),
+                "今日越えて".to_owned(),
+                "浅き夢見し".to_owned(),
+                "酔ひもせず".to_owned()
             ],
             &[]
         ));
 
         assert!(check_word_mute_impl(
             &texts,
-            &["yellow fox".to_string(), "mastodon".to_string()],
+            &["yellow fox".to_owned(), "mastodon".to_owned()],
             &[hiragana_1.clone()]
         ));
 
         assert!(check_word_mute_impl(
             &texts,
-            &["yellow fox".to_string(), "mastodon".to_string()],
+            &["yellow fox".to_owned(), "mastodon".to_owned()],
             &[hiragana_2.clone()]
         ));
 
         assert!(!check_word_mute_impl(
             &texts,
-            &["yellow fox".to_string(), "mastodon".to_string()],
+            &["yellow fox".to_owned(), "mastodon".to_owned()],
             &[katakana_1.clone()]
         ));
 
         assert!(!check_word_mute_impl(
             &texts,
-            &["yellow fox".to_string(), "mastodon".to_string()],
+            &["yellow fox".to_owned(), "mastodon".to_owned()],
             &[katakana_2.clone()]
         ));
 
         assert!(check_word_mute_impl(
             &texts,
-            &["brown fox".to_string(), "mastodon".to_string()],
+            &["brown fox".to_owned(), "mastodon".to_owned()],
             &[katakana_1.clone()]
         ));
 
         assert!(check_word_mute_impl(
             &texts,
-            &["brown fox".to_string(), "mastodon".to_string()],
+            &["brown fox".to_owned(), "mastodon".to_owned()],
             &[katakana_2.clone()]
         ));
 
         assert!(check_word_mute_impl(
             &texts,
-            &["yellow fox".to_string(), "dog".to_string()],
+            &["yellow fox".to_owned(), "dog".to_owned()],
             &[katakana_1.clone()]
         ));
 
         assert!(check_word_mute_impl(
             &texts,
-            &["yellow fox".to_string(), "dog".to_string()],
+            &["yellow fox".to_owned(), "dog".to_owned()],
             &[katakana_2.clone()]
         ));
 
         assert!(check_word_mute_impl(
             &texts,
-            &["yellow fox".to_string(), "mastodon".to_string()],
+            &["yellow fox".to_owned(), "mastodon".to_owned()],
             &[hiragana_1.clone(), katakana_1.clone()]
         ));
 
         assert!(check_word_mute_impl(
             &texts,
-            &["😇".to_string(), "🥲".to_string(), "🥴".to_string()],
+            &["😇".to_owned(), "🥲".to_owned(), "🥴".to_owned()],
             &[]
         ));
 
         assert!(!check_word_mute_impl(
             &texts,
-            &["🙂".to_string(), "🥲".to_string(), "🥴".to_string()],
+            &["🙂".to_owned(), "🥲".to_owned(), "🥴".to_owned()],
             &[]
         ));
 
diff --git a/packages/backend-rs/src/misc/get_image_size.rs b/packages/backend-rs/src/misc/get_image_size.rs
index 1964c9cbd9..bc5222f054 100644
--- a/packages/backend-rs/src/misc/get_image_size.rs
+++ b/packages/backend-rs/src/misc/get_image_size.rs
@@ -68,7 +68,7 @@ pub async fn get_image_size_from_url(url: &str) -> Result<ImageSize, Error> {
 
     if attempted {
         tracing::warn!("attempt limit exceeded: {}", url);
-        return Err(Error::TooManyAttempts(url.to_string()));
+        return Err(Error::TooManyAttempts(url.to_owned()));
     }
 
     tracing::info!("retrieving image from {}", url);
diff --git a/packages/backend-rs/src/misc/note/summarize.rs b/packages/backend-rs/src/misc/note/summarize.rs
index 9649fc9345..0a6240d194 100644
--- a/packages/backend-rs/src/misc/note/summarize.rs
+++ b/packages/backend-rs/src/misc/note/summarize.rs
@@ -15,12 +15,12 @@ pub fn summarize_impl(
 
     match file_ids.len() {
         0 => (),
-        1 => buf.push("📎".to_string()),
+        1 => buf.push("📎".to_owned()),
         n => buf.push(format!("📎 ({})", n)),
     };
 
     if has_poll {
-        buf.push("📊".to_string())
+        buf.push("📊".to_owned())
     }
 
     buf.join(" ")
@@ -94,7 +94,7 @@ mod unit_test {
     fn summarize_note() {
         let note = NoteLike {
             file_ids: vec![],
-            text: Some("Hello world!".to_string()),
+            text: Some("Hello world!".to_owned()),
             cw: None,
             has_poll: false,
         };
@@ -102,26 +102,26 @@ mod unit_test {
 
         let note_with_cw = NoteLike {
             file_ids: vec![],
-            text: Some("Hello world!".to_string()),
-            cw: Some("Content warning".to_string()),
+            text: Some("Hello world!".to_owned()),
+            cw: Some("Content warning".to_owned()),
             has_poll: false,
         };
         assert_eq!(summarize!(note_with_cw), "Content warning");
 
         let note_with_file_and_cw = NoteLike {
-            file_ids: vec!["9s7fmcqogiq4igin".to_string()],
+            file_ids: vec!["9s7fmcqogiq4igin".to_owned()],
             text: None,
-            cw: Some("Selfie, no ec".to_string()),
+            cw: Some("Selfie, no ec".to_owned()),
             has_poll: false,
         };
         assert_eq!(summarize!(note_with_file_and_cw), "Selfie, no ec 📎");
 
         let note_with_files_only = NoteLike {
             file_ids: vec![
-                "9s7fmcqogiq4igin".to_string(),
-                "9s7qrld5u14cey98".to_string(),
-                "9s7gebs5zgts4kca".to_string(),
-                "9s5z3e4vefqd29ee".to_string(),
+                "9s7fmcqogiq4igin".to_owned(),
+                "9s7qrld5u14cey98".to_owned(),
+                "9s7gebs5zgts4kca".to_owned(),
+                "9s5z3e4vefqd29ee".to_owned(),
             ],
             text: None,
             cw: None,
@@ -131,13 +131,13 @@ mod unit_test {
 
         let note_all = NoteLike {
             file_ids: vec![
-                "9s7fmcqogiq4igin".to_string(),
-                "9s7qrld5u14cey98".to_string(),
-                "9s7gebs5zgts4kca".to_string(),
-                "9s5z3e4vefqd29ee".to_string(),
+                "9s7fmcqogiq4igin".to_owned(),
+                "9s7qrld5u14cey98".to_owned(),
+                "9s7gebs5zgts4kca".to_owned(),
+                "9s5z3e4vefqd29ee".to_owned(),
             ],
-            text: Some("Hello world!".to_string()),
-            cw: Some("Content warning".to_string()),
+            text: Some("Hello world!".to_owned()),
+            cw: Some("Content warning".to_owned()),
             has_poll: true,
         };
         assert_eq!(summarize!(note_all), "Content warning 📎 (4) 📊");
diff --git a/packages/backend-rs/src/misc/reaction.rs b/packages/backend-rs/src/misc/reaction.rs
index 01441b90a3..e6b699d59a 100644
--- a/packages/backend-rs/src/misc/reaction.rs
+++ b/packages/backend-rs/src/misc/reaction.rs
@@ -128,12 +128,12 @@ mod unit_test {
     #[test]
     fn decode_reaction() {
         let unicode_emoji_1 = DecodedReaction {
-            reaction: "⭐".to_string(),
+            reaction: "⭐".to_owned(),
             name: None,
             host: None,
         };
         let unicode_emoji_2 = DecodedReaction {
-            reaction: "🩷".to_string(),
+            reaction: "🩷".to_owned(),
             name: None,
             host: None,
         };
@@ -145,23 +145,23 @@ mod unit_test {
         assert_ne!(super::decode_reaction("🩷"), unicode_emoji_1);
 
         let unicode_emoji_3 = DecodedReaction {
-            reaction: "🖖🏿".to_string(),
+            reaction: "🖖🏿".to_owned(),
             name: None,
             host: None,
         };
         assert_eq!(super::decode_reaction("🖖🏿"), unicode_emoji_3);
 
         let local_emoji = DecodedReaction {
-            reaction: ":meow_melt_tears@.:".to_string(),
-            name: Some("meow_melt_tears".to_string()),
+            reaction: ":meow_melt_tears@.:".to_owned(),
+            name: Some("meow_melt_tears".to_owned()),
             host: None,
         };
         assert_eq!(super::decode_reaction(":meow_melt_tears:"), local_emoji);
 
         let remote_emoji_1 = DecodedReaction {
-            reaction: ":meow_uwu@some-domain.example.org:".to_string(),
-            name: Some("meow_uwu".to_string()),
-            host: Some("some-domain.example.org".to_string()),
+            reaction: ":meow_uwu@some-domain.example.org:".to_owned(),
+            name: Some("meow_uwu".to_owned()),
+            host: Some("some-domain.example.org".to_owned()),
         };
         assert_eq!(
             super::decode_reaction(":meow_uwu@some-domain.example.org:"),
@@ -169,9 +169,9 @@ mod unit_test {
         );
 
         let remote_emoji_2 = DecodedReaction {
-            reaction: ":C++23@xn--eckwd4c7c.example.org:".to_string(),
-            name: Some("C++23".to_string()),
-            host: Some("xn--eckwd4c7c.example.org".to_string()),
+            reaction: ":C++23@xn--eckwd4c7c.example.org:".to_owned(),
+            name: Some("C++23".to_owned()),
+            host: Some("xn--eckwd4c7c.example.org".to_owned()),
         };
         assert_eq!(
             super::decode_reaction(":C++23@xn--eckwd4c7c.example.org:"),
@@ -179,14 +179,14 @@ mod unit_test {
         );
 
         let invalid_reaction_1 = DecodedReaction {
-            reaction: ":foo".to_string(),
+            reaction: ":foo".to_owned(),
             name: None,
             host: None,
         };
         assert_eq!(super::decode_reaction(":foo"), invalid_reaction_1);
 
         let invalid_reaction_2 = DecodedReaction {
-            reaction: ":foo&@example.com:".to_string(),
+            reaction: ":foo&@example.com:".to_owned(),
             name: None,
             host: None,
         };
diff --git a/packages/backend-rs/src/misc/system_info.rs b/packages/backend-rs/src/misc/system_info.rs
index 4b31ceaaee..d5191c16f6 100644
--- a/packages/backend-rs/src/misc/system_info.rs
+++ b/packages/backend-rs/src/misc/system_info.rs
@@ -38,9 +38,9 @@ pub fn cpu_info() -> Result<Cpu, SysinfoPoisonError> {
         model: match system_info.cpus() {
             [] => {
                 tracing::debug!("failed to get CPU info");
-                "unknown".to_string()
+                "unknown".to_owned()
             }
-            cpus => cpus[0].brand().to_string(),
+            cpus => cpus[0].brand().to_owned(),
         },
         cores: system_info.cpus().len() as u16,
     })
diff --git a/packages/backend-rs/src/service/antenna/process_new_note.rs b/packages/backend-rs/src/service/antenna/process_new_note.rs
index 13fc7fdcbb..0588c3c3f3 100644
--- a/packages/backend-rs/src/service/antenna/process_new_note.rs
+++ b/packages/backend-rs/src/service/antenna/process_new_note.rs
@@ -71,7 +71,7 @@ async fn add_note_to_antenna(antenna_id: &str, note: &Note) -> Result<(), Error>
         .await?;
 
     // for streaming API
-    stream::antenna::publish(antenna_id.to_string(), note).await?;
+    stream::antenna::publish(antenna_id.to_owned(), note).await?;
 
     Ok(())
 }
diff --git a/packages/backend-rs/src/service/note/watch.rs b/packages/backend-rs/src/service/note/watch.rs
index 144f4e2360..3a5e9a0bf3 100644
--- a/packages/backend-rs/src/service/note/watch.rs
+++ b/packages/backend-rs/src/service/note/watch.rs
@@ -13,9 +13,9 @@ pub async fn watch_note(
         note_watching::Entity::insert(note_watching::ActiveModel {
             id: ActiveValue::set(gen_id_at(now)),
             created_at: ActiveValue::set(now.into()),
-            user_id: ActiveValue::Set(watcher_id.to_string()),
-            note_user_id: ActiveValue::Set(note_author_id.to_string()),
-            note_id: ActiveValue::Set(note_id.to_string()),
+            user_id: ActiveValue::Set(watcher_id.to_owned()),
+            note_user_id: ActiveValue::Set(note_author_id.to_owned()),
+            note_id: ActiveValue::Set(note_id.to_owned()),
         })
         .exec(db_conn().await?)
         .await?;
diff --git a/packages/backend-rs/src/service/push_notification.rs b/packages/backend-rs/src/service/push_notification.rs
index 6abe5e1866..cfe1d99ae8 100644
--- a/packages/backend-rs/src/service/push_notification.rs
+++ b/packages/backend-rs/src/service/push_notification.rs
@@ -55,7 +55,7 @@ pub enum PushNotificationKind {
 
 fn compact_content(mut content: serde_json::Value) -> Result<serde_json::Value, Error> {
     if !content.is_object() {
-        return Err(Error::InvalidContent("not a JSON object".to_string()));
+        return Err(Error::InvalidContent("not a JSON object".to_owned()));
     }
 
     let object = content.as_object_mut().unwrap();
@@ -69,9 +69,7 @@ fn compact_content(mut content: serde_json::Value) -> Result<serde_json::Value,
             .get("note")
             .unwrap()
             .get("renote")
-            .ok_or(Error::InvalidContent(
-                "renote object is missing".to_string(),
-            ))?
+            .ok_or(Error::InvalidContent("renote object is missing".to_owned()))?
     } else {
         object.get("note").unwrap()
     }
@@ -79,7 +77,7 @@ fn compact_content(mut content: serde_json::Value) -> Result<serde_json::Value,
 
     if !note.is_object() {
         return Err(Error::InvalidContent(
-            "(re)note is not an object".to_string(),
+            "(re)note is not an object".to_owned(),
         ));
     }
 
@@ -101,8 +99,8 @@ fn compact_content(mut content: serde_json::Value) -> Result<serde_json::Value,
     note_object.remove("reply");
     note_object.remove("renote");
     note_object.remove("user");
-    note_object.insert("text".to_string(), text.into());
-    object.insert("note".to_string(), note);
+    note_object.insert("text".to_owned(), text.into());
+    object.insert("note".to_owned(), note);
 
     Ok(serde_json::from_value(Json::Object(object.clone()))?)
 }
@@ -121,14 +119,14 @@ async fn get_mastodon_subscription_info(
     if token.is_none() {
         unsubscribe(db, subscription_id).await?;
         return Err(Error::InvalidSubscription(
-            "access token not found".to_string(),
+            "access token not found".to_owned(),
         ));
     }
     let token = token.unwrap();
 
     if token.app_id.is_none() {
         unsubscribe(db, subscription_id).await?;
-        return Err(Error::InvalidSubscription("no app ID".to_string()));
+        return Err(Error::InvalidSubscription("no app ID".to_owned()));
     }
     let app_id = token.app_id.unwrap();
 
@@ -139,7 +137,7 @@ async fn get_mastodon_subscription_info(
 
     if client.is_none() {
         unsubscribe(db, subscription_id).await?;
-        return Err(Error::InvalidSubscription("app not found".to_string()));
+        return Err(Error::InvalidSubscription("app not found".to_owned()));
     }
 
     Ok((token.token, client.unwrap().name))
@@ -152,11 +150,11 @@ async fn encode_mastodon_payload(
 ) -> Result<String, Error> {
     let object = content
         .as_object_mut()
-        .ok_or(Error::InvalidContent("not a JSON object".to_string()))?;
+        .ok_or(Error::InvalidContent("not a JSON object".to_owned()))?;
 
     if subscription.app_access_token_id.is_none() {
         unsubscribe(db, &subscription.id).await?;
-        return Err(Error::InvalidSubscription("no access token".to_string()));
+        return Err(Error::InvalidSubscription("no access token".to_owned()));
     }
 
     let (token, client_name) = get_mastodon_subscription_info(
@@ -166,7 +164,7 @@ async fn encode_mastodon_payload(
     )
     .await?;
 
-    object.insert("access_token".to_string(), serde_json::to_value(token)?);
+    object.insert("access_token".to_owned(), serde_json::to_value(token)?);
 
     // Some apps expect notification_id to be an integer,
     // but doesn’t break when the ID doesn’t match the rest of API.
@@ -187,7 +185,7 @@ async fn encode_mastodon_payload(
             .transpose()?
             .unwrap_or_default();
 
-        object.insert("notification_id".to_string(), timestamp.into());
+        object.insert("notification_id".to_owned(), timestamp.into());
     }
 
     let res = serde_json::to_string(&content)?;
@@ -273,7 +271,7 @@ pub async fn send_push_notification(
     // TODO: refactoring
     let mut payload = if use_mastodon_api {
         // Content generated per subscription
-        "".to_string()
+        "".to_owned()
     } else {
         // Format the `content` passed from the TypeScript backend
         // for Firefish push notifications
diff --git a/packages/backend-rs/src/service/stream.rs b/packages/backend-rs/src/service/stream.rs
index 236f34fcad..25f5802eef 100644
--- a/packages/backend-rs/src/service/stream.rs
+++ b/packages/backend-rs/src/service/stream.rs
@@ -80,13 +80,13 @@ pub async fn publish_to_stream(
     value: Option<String>,
 ) -> Result<(), Error> {
     let channel = match stream {
-        Stream::Internal => "internal".to_string(),
-        Stream::CustomEmoji => "broadcast".to_string(),
+        Stream::Internal => "internal".to_owned(),
+        Stream::CustomEmoji => "broadcast".to_owned(),
         Stream::Moderation { moderator_id } => format!("adminStream:{moderator_id}"),
         Stream::User { user_id } => format!("user:{user_id}"),
         Stream::Channel { channel_id } => format!("channelStream:{channel_id}"),
         Stream::Note { note_id } => format!("noteStream:{note_id}"),
-        Stream::Notes => "notesStream".to_string(),
+        Stream::Notes => "notesStream".to_owned(),
         Stream::UserList { list_id } => format!("userListStream:{list_id}"),
         Stream::Main { user_id } => format!("mainStream:{user_id}"),
         Stream::Drive { user_id } => format!("driveStream:{user_id}"),
@@ -103,7 +103,7 @@ pub async fn publish_to_stream(
         format!(
             "{{\"type\":\"{}\",\"body\":{}}}",
             kind,
-            value.unwrap_or_else(|| "null".to_string()),
+            value.unwrap_or_else(|| "null".to_owned()),
         )
     } else {
         value.ok_or(Error::InvalidContent)?
diff --git a/packages/backend-rs/src/util/error_chain.rs b/packages/backend-rs/src/util/error_chain.rs
index 4d1341dc05..d19c99ae76 100644
--- a/packages/backend-rs/src/util/error_chain.rs
+++ b/packages/backend-rs/src/util/error_chain.rs
@@ -46,7 +46,7 @@ mod unit_test {
             Err(InnerError1)
         }
         fn causes_inner_error_2() -> Result<(), InnerError2> {
-            Err(InnerError2("foo".to_string()))
+            Err(InnerError2("foo".to_owned()))
         }
 
         fn causes_error_1() -> Result<(), ErrorVariants> {
diff --git a/packages/backend-rs/src/util/id.rs b/packages/backend-rs/src/util/id.rs
index c7f5f294dd..4cce5897f0 100644
--- a/packages/backend-rs/src/util/id.rs
+++ b/packages/backend-rs/src/util/id.rs
@@ -58,7 +58,7 @@ pub fn get_timestamp(id: &str) -> Result<i64, InvalidIdError> {
     if let Some(n) = n {
         Ok(n as i64 + TIME_2000)
     } else {
-        Err(InvalidIdError { id: id.to_string() })
+        Err(InvalidIdError { id: id.to_owned() })
     }
 }